A manufacturing process of a semiconductor device includes a process of forming a recess, such as a hole or a trench, in an insulating film and of filling the same with a silicon film, such as an amorphous silicon film so as to form an electrode. In general, a chemical vapor deposition (CVD) method has been used for the silicon film forming process. However, when a CVD method is used to fill a deep hole or trench with a silicon film, the step coverage becomes poor, resulting in the creation of voids. Voids created in the silicon film to be used as an electrode increase the resistance. Accordingly, the silicon film having as less voids as possible is required.
In contrast, for example, a technique has been proposed in which a silicon film is formed in a recess such as a hole or a trench and is etched in a V-shaped cross-section, and in which the recess is then filled with a silicon film again. According to this technique, a void-free filling can be achieved.
However, in recent years, the semiconductor devices have become smaller. In addition, the width of a recess to be filled with a silicon film has also become narrower. Thus, it is difficult to make a void-free filling by means of the V-shaped etching technique as described in the related art.